Resistor structure



Jan. 24, 1961 R. E. DU BOIS RESISTOR STRUCTURE 2 Sheets-Sheet 1 Filed 001'.- 27, 1959 INVENTOR ROBERT E DUBO/S ATTORNEY Jan. 24, 1961 u 5015 2,969,516

RESISTOR STRUCTURE Filed Oct. '27. 1959 2 Sheets-Sheet 2 INVENTOT:

ROBERT E 0050/5 ATTORNEY United dtates Patent 2,969,516 RESISTOR STRUCTURE Robert E. Du Bois, 7541 Woodmar Ave., Hammond, Ind.

Filed Oct. 27, 1959, Ser. No. 848,960

4 Claims. (Cl. 338-284) This invention relates generally to resistor grids and more particularly to zig-zag resistor grids formed in a novel manner from a single piece of resistance material.

The primary object of this invention is to provide a resistor grid of the zig-zag type in which practically no material loss is incurred during formation of the grid.

A specific object of this invention is to provide a novel resistor structure including an improved manner of connection between a grid element and the frame members of the structure.

A further object of this invention is to provide an improved zig-zag resistor grid which is economical to manufacture.

Another object of this invention is to provide a Zig-zag resistor grid wherein adjacent sections of the grid are offset from each other transversely of the plane of the grid to obtain a more efiicient temperature gradient control of the grid when circulating cooling air passes the grid sections.

With the foregoing and other objects in view, the invention resides in the following specification and appended claims, certain embodiments and details of construction being illustrated in the acompanying drawings in which:

Figure l is a fragmentary, partially sectioned view in front elevation of the resistor structure of this invention;

Figure 2 is an end view taken along the lines 22 of Figure 1;

Figure 3 is a plan view taken along the lines 33 of Figure 1; and

Figure 4 is an expanded and exploded perspective view of the grid element of this invention shown together with the frame mounting clips for the grid.

Referring more particularly to Figure l, the resistor structure of this invention generally indicated at is illustrated as including end frame members 11 and 12. interconnecting members 11 and 12 to effect a rigid frame structure is a pair of spaced bolts 13 and 14. Each bolt is surrounded by an insulating sleeve 15 and a plurality of spacing and insulating washers 16. External to members 11 and 12 the projecting threaded ends of bolts 13 and 14 are capped with suitable washers 17 and nuts 18. It is obvious that upon tightening nuts 18 a rigid frame 10 is assured.

Referring to Figure 4, a zig-zag resistor grid 19 is illustrated as being formed from a single piece of resistor material. Grid 19 includes a plurality of longitudinally spaced grid sections 20, 21 and 22 with each section including a pair of legs 23 and 24 and all the legs being of the same length. In each section as the legs 23 and 24 are joined by a bridging section 25. Bridging section 25 is folded upon itself to leave a gap 26, for a purpose to be described, during the forming stages of the grid. The section 20 is joined to the section 21, for example by a planar bridging section 27. Each section 27 is provided with a hole 28 through which bolt 14 may pass to secure one side of the grid to the frame 10. As illustrated, the bridging sections 25 are alternately folded in opposite directions. In this manner the sections 20, 21 and 22 are "ice arranged in a lateral offset relationship tothe central longitudinal plane of the grid 19. The only waste material resulting from the formation of this grid arises from the punching of holes 28. It will be readily obvious to a metal worker that no other material is lost in taking a flat piece of resistor material, slitting the material in alternately opposite directions to form legs 23 and 24 and then reversely folding the bridging sections 25 in order to achieve the offset adjacent sections 20, 21 and 22 as illus- 'trated.

Grid mounting clips 29 are clamped between the washers 16 on bolt 13. Each clip includes a bolt receiving hole '30 and a pair of outwardly extending, spaced legs 31 and 32. The spacing between the legs 31 and 32 permits the relatively free reception of the material at the base of the fold of a bridging section 25. Leg 31 enters into the gap 26 in section 25 to achieve a sliding joint while restraining the section 25 against longitudinal movement relative to the plane of the grid. The leg 32 rides along the outer surface of the section 25 as is clearly shown in Figure 2, and restrains the section against transverse movement relative to the plane of the grid. The clips 29 illustrated in Figure 4 are identical; they are simply alternately, reversely mounted on bolt 13 during assembly of the resistor to agree in position with the positions of the alternately offset bridging sections 25.

With the grid 19 mounted in the frame 10 in the manner described, the bridging sections 27 are fixed against movement. However, the bridging sections 25, having a sliding fit or joint relationship with fixed clips 29, may move with the expansion and contraction of legs 23 and 24 under varying temperature conditions to avoid warping and/or breaking of the grid. Thus as viewed in Figure l, the grid 19 is movably connected with the frame 10 along the upper side, and is fixedly connected with the frame along the lower side.

Terminal pieces 33 and 34 are secured about bolt 14 to make contact with two selected bridging sections 27.

Preferably the legs 23 and 24 of the grid 19 are angled throughout most of their length to add strength to the grid. Another manner of securing this additional strength is to form an arc in each leg by any suitable means.

By having the adjacent sections such as 20, 21 and 22 offset, better cooling of the grid 19 is attained under air draft conditions, since the displacement of the sections assists in the avoidance of hot spots. Thus a more uniform cooling of grid 19 is possible.

Thus it is seen that this invention provides a new and useful grid element and resistor structure having structural and functional advantages over the prior art in the form of economies of production, form of erection and the adaptability to better cooling.

It is realized that the invention may be subject to numerous obvious structural modifications well within the purview of this inventor who intends only to be limited to a liberal interpretation of this specification and the appended claims.

I claim:

1. A resistor structure comprising spaced frame members, plural spaced means interconnecting said frame members to complete a rigid frame, a zig-Zag resistor grid formed from a single piece of resistor material, said grid including a plurality of connected, spaced adjacent grid sections of similar length with each section being offset oppositely from adjacent sections to either side of a central plane through the longitudinal axis of the grid, each said grid section including a pair of legs integrally joined together by a folding bridging section along one side of the grid with the direction of fold of said bridging sections alternating from one grid section to the next, means connecting said folding bridging sections to one of said frame interconnecting means, said grid further including a plurality of planar bridging sections along the other side of the grid with one leg from each of a pair of adjacent grid sections terminating in one of said planar bridging sections, and means to connect the planar bridging sections to a second of said spaced frame member interconnecting means.

2. The invention according to claim 1 wherein the means to connect the folded bridging sections to a frame member interconnecting means constitutes a sliding joint so as to permit relative movement between the grid sections and the frame in the plane of each grid section.

3. The invention according to claim 1, wherein the means to connect the folded bridging sections to a frame member interconnecting means includes a clip with an outwardly extending leg, said clip being rigid with the frame and said leg entering into the folded portion of If each of said folded bridging sections to thereby connect the bridging sections to the frame in a manner so as to permit relative movement between the grid sections and the frame in the plane of each grid section.

4. The invention according to claim 3 wherein each clip is provided with a second outwardly extending leg spaced from said first leg and being adapted to engage the exterior of a folded bridging section to restrain the grid sections against transverse movement.

References Cited in the file of this patent UNITED STATES PATENTS 1,719,179 Hayden July 2, 1929 15 2,856,496 Fisher Oct. 14, 1958 Grifies et a1 Oct. 28, 1958 

